A voice recognition process has already been put to practical use for creating text data based on vocal content for voice data based on voice produced by a speaker. Text data created by the voice recognition process is in practical use for a variety of applications such as an audio-typing process to write down the content of the dialogue at a call center, for example. Text data may also be created by a word unit and utilized as a keyword for summarizing the content of the dialogue at a call center, for example, and further for retrieving related information.
In a voice recognition process, voice is recognized by a pronunciation unit, such as a syllable, on the basis of a feature quantity obtained by analyzing voice data based on vocalization and voice is recognized as a phrase listed in a word dictionary, by performing a matching operation referring to a word dictionary which lists phrases in a method such as the Word Spotting, for example. A technique to increase the vocabulary is described in Japanese Laid-Open Patent Publication No. 11-7292, for example, as a method to raise the recognition rate.